Mazda: Turbo key to rotary engine revival

Mazda has revealed further details of its next-generation rotary engine following the reveal of its show-stopping RX-Vision concept car at the 2015 Tokyo motor show, including confirmation it will be turbocharged and the car it will power will be built off a dedicated sports car platform.

Although it has yet to provide a definitive timeline on when it will return to production in the RX-9 sportscar that is expected to be spawned from the concept car, the company's head of research and development, Kiyoshi Fujiwara, told Australian media that prototype test vehicles will begin on-road trials soon.

The new-generation engine is an extension of the 16X rotary concept that was previewed at the 2013 Tokyo show, which means the engine has a capacity of 1.6-litres (up from 1.3-litres in the 13B Renesis engine that powered the RX-8 which was discontinued in 2012) and features a revised combustion chamber with a longer stroke to increase low-speed torque and a direct fuel injection system to improve fuel efficiency.

"Unfortunately I cannot say when [the rotary-powered sportscar] will be produced, but we have all the technical solutions all in place," he said.

"Now we need time to validate the quality issues by actual testing with prototype engine. That kind of validation is needed, because we have had bad quality issues with that engine in the past. We need to ensure we completely validate the quality issues before making this decision.

"But we have a plan and prototype testing will begin soon."

However, Fujiwara did concede, for the first time, that it will feature forced induction in a bid to maximise performance and further improve its economy saying "turbo charging is one of the big contributors for the future rotary engine."

He also indicated that Mazda's previous decision to twin the third-generation MX-5 and RX-8 off the same rear-drive architecture compromised both vehicles, and the company learnt from that lesson with the RX-9 set to be built on its own dedicated platform that will introduce new construction techniques and materials that will eventually filter down to Mazda's mainstream passenger cars.

"The former MX-5 used the same platform as RX-8, but both cars were not the ideal situation. The NC MX-5 should have been on another platform," he admitted.

"The new roadster MX-5 has a completely new platform just for MX-5 and this kind of sportscar cannot use the current passenger car platform; it is quite low and lighter weight is required so we have to consider more clever solutions.

"Looking at our history for sportscars, it has always had new technologies like RX-8, which had new construction methods.

"That kind of technology is used in sportscars [first], and then can be delivered to passenger cars. This RX-Vision maybe has a new technology for body and chassis that can be delivered to next-generation Mazda passenger cars."

While Fujiwara admitted the Skyactiv-R rotary engine will be turbo charged, he was adamant that he wanted it to return to production in a pure sportscar without any form of hybrid powertrain. But also conceded that future emission output regulations may force the adoption of electric assistance in the future.

"First I would like to introduce rotary engine by itself. Personally, I want to introduce new rotary engine without electrification in the first step," he said

"But with severe requirement for emissions coming, then we will add some form of electrification later."